The legal battle between Steven Tyler’s ex-manager Allen Kovac and the rocker’s attorney Dina LaPolt over Tyler’s failed multimillion-dollar “American Idol” deal has spilled over to hair-metal band Mötley Crüe, Page Six has learned.

According to court documents filed in Los Angeles last week, Kovac claims LaPolt — “in retaliation” against him for filing a claim that LaPolt botched Tyler’s “Idol” deal to the tune of $8 million — has been “conspiring” to “set up a competing management company” to steal away a “world-famous rock band” that Kovac has repped for 15 years. (The band is not named in the suit, but sources confirm it’s Mötley Crüe.)

According to the suit, LaPolt — who’s said to be filming a reality-TV show called “Lipstick Law” — told Crüe’s business manager: “I am going to be the person that takes Allen Kovac down. He doesn’t know who he is [bleep]ing with . . . this is what happens when someone [bleeps] with me, it’ll all go down and it’ll be dirty.”

The suit alleges that she’s tried to drive a wedge between band members to “disrupt” the act, and that she gathered a team including Live Nation executive chairman Irving Azoff, Howard Kaufman, David Weise and Carl Stubner to take over the band’s business. (In the band’s already thorny legal history, Stubner was previously sued by Mötley Crüe in 2007, when he was Tommy Lee’s manager.)

LaPolt’s attorney, Christine Lepera, told us LaPolt and her law firm “vehemently dispute and deny all of the allegations against them in both the initial and amended complaint. They intend to vigorously defend and take all other steps to rectify the damages caused to them by this action. Defendants believe they are the target of an undeserved attack, and will be filing a response in due course. Defendants, will not, however, litigate this case in the press.”

Kovac’s lawyer, Skip Miller, said: “This is a very serious lawsuit involving an attorney’s duty of loyalty and honor. The case will eventually be put before a jury. They will decide it on the merits.”